add explicit upgrade command

Command/Upgrade.hs

@@ -0,0 +1,22 @@
+{- git-annex command
+ -
+ - Copyright 2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Command.Upgrade where
+
+import Command
+
+command :: [Command]
+command = [Command "upgrade" paramNothing seek "upgrade repository layout"]
+
+seek :: [CommandSeek]
+seek = [withNothing start]
+
+start :: CommandStartNothing
+start = do
+	-- The actual upgrading is handled by just running any command,
+	-- so nothing extra needs to be done.
+	return $ Just $ return $ Just $ return True